JP2018081165A - Image forming apparatus, estimation method, and estimation program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can accurately estimate the thickness of a photoreceptor.SOLUTION: An image forming apparatus comprises: photoreceptors; charging rollers for charging the photoreceptors; detection parts for detecting the values of currents flowing in the photoreceptors or the charging rollers by applying voltages to the charging rollers; an acquisition part for acquiring an environmental value indicating an environmental state inside the image forming apparatus; and a control device that estimates the thickness of the photoreceptors on the basis of the values of the currents detected by the detection parts when the situation where the environmental value is within a predetermined range Δc continues for a predetermined time th or more.SELECTED DRAWING: Figure 5

Description

  The present disclosure relates to a technique for estimating a film thickness of a photoreceptor provided in an image forming apparatus.

  Image forming apparatuses such as MFPs (Multi-Functional Peripherals) are widely used. An electrophotographic image forming apparatus includes, as a printing process, a step of charging a photoconductor with a charging roller, a step of exposing the photoconductor according to an image pattern in response to a print instruction, and an electrostatic latent image formed by the exposure. And developing the toner image as a toner image.

  When the photoreceptor is used, its surface is worn away. When the film thickness on the surface of the photoreceptor is reduced, printing failure occurs. Therefore, the user needs to replace the photoconductor regularly. In order to grasp the replacement time of the photoconductor, it is important to accurately detect the film thickness of the photoconductor. In recent years, various techniques for estimating the film thickness of a photoreceptor have been developed.

  An example of a technique for estimating the film thickness will be described. As described above, the photoreceptor is charged by the charging roller. When the film thickness of the photoconductor is reduced, the current flowing through the charging roller when a voltage is applied to the charging roller (hereinafter also referred to as “charging current”) changes. That is, the magnitude of the charging current correlates with the film thickness of the photoreceptor. Focusing on this point, the image forming apparatus detects the charging current and estimates the film thickness of the photoconductor based on the magnitude of the charging current. For example, JP-A-2015-148789 (Patent Document 1), JP-A-2008-107571 (Patent Document 2), and JP-A-2011-28102 are methods for estimating the film thickness based on such a charging current. It is disclosed in the gazette (patent document 3) etc.

JP2015-148789A JP 2008-107571 A JP 2011-28102 A

  The charging current varies depending on the environment such as temperature and humidity. Therefore, when the charging current is not stable, the film thickness of the photoreceptor cannot be estimated accurately. Such a problem appears particularly prominently in an environment in which changes in temperature and humidity are severe. Therefore, a technique for accurately estimating the film thickness of the photoreceptor is desired.

  The present disclosure has been made in order to solve the above-described problems, and an object in one aspect is to provide an image forming apparatus that can accurately estimate the film thickness of a photoreceptor. An object in another aspect is to provide an estimation method capable of accurately estimating the film thickness of the photoreceptor. Still another object of the present invention is to provide an estimation program that can accurately estimate the film thickness of a photoreceptor.

  According to an aspect, the image forming apparatus detects a value of a current flowing through the photosensitive member or the charging roller by applying a voltage to the photosensitive member, a charging roller for charging the photosensitive member, and the charging roller. A detection unit for acquiring an environmental value representing an environmental state in the image forming apparatus, and when the environmental value is within a predetermined range for a predetermined time or longer. And a control device that estimates the film thickness of the photoconductor based on the value of the current detected by the detection unit.

  Preferably, the control device calculates a reduction rate of the film thickness based on the amount of change in the film thickness and the usage amount of the photoconductor at the time when the film thickness is estimated, and the control device calculates the thickness based on the reduction rate. Predict the life of the photoreceptor.

  Preferably, when the estimated film thickness is less than a predetermined value, the control device outputs that the lifetime of the photoconductor has come.

  Preferably, the acquisition unit includes a temperature sensor for detecting a temperature in the image forming apparatus as the environmental value.

  Preferably, the acquisition unit includes a humidity sensor for detecting humidity in the image forming apparatus as the environmental value.

  Preferably, the control device estimates the film thickness based on the current value, the temperature, and the humidity.

  Preferably, the control device narrows the predetermined range as the temperature detected by the temperature sensor is lower.

  Preferably, the value of the current used for the film thickness estimation process is detected when the number of printed sheets in the predetermined time by the image forming apparatus is less than the predetermined number.

  Preferably, the control device performs a determination process for determining a magnitude of a voltage to be applied to the charging roller based on a current value detected by the detection unit during a printing process by the image forming apparatus. Run. The value of the current detected by the detection unit during the determination process is used for the estimation of the film thickness.

  According to another aspect, an estimation method for estimating a film thickness of a photoconductor provided in an image forming apparatus includes applying a voltage to a charging roller for charging the photoconductor, and applying the voltage to the charging roller. Detecting a value of a current flowing through the photosensitive member or the charging roller by applying a voltage, a step of acquiring an environmental value representing an environmental state in the image forming apparatus, and the environmental value is within a predetermined range. And a step of estimating the film thickness of the photoconductor based on the value of the current detected in the detecting step when the state of being present continues for a predetermined time or more.

  According to another aspect, an estimation program for estimating a film thickness of a photoreceptor provided in an image forming apparatus includes applying a voltage to a charging roller for charging the photoreceptor to the image forming apparatus; Detecting a value of a current flowing through the photosensitive member or the charging roller by applying the voltage to the charging roller, obtaining an environmental value representing an environmental state in the image forming apparatus, and the environmental value. The step of estimating the film thickness of the photoconductor is executed based on the value of the current detected in the step of detecting when the state of being within the predetermined range continues for a predetermined time or more.

In one aspect, the film thickness of the photoreceptor can be accurately estimated.
The above and other objects, features, aspects and advantages of the present invention will become apparent from the following detailed description of the present invention taken in conjunction with the accompanying drawings.

It is a figure which shows an example of the internal structure of the image forming apparatus according to 1st Embodiment. It is a figure which shows an example of a structure required in order to estimate the film thickness of a photoreceptor. It is a figure which shows an example of a structure required in order to estimate the film thickness of a photoreceptor. It is a figure which shows an example of correlation with a charging current and the film thickness of a photoreceptor. It is a figure which shows an example of transition of an environmental value. It is a figure which shows an example of a function structure of the image forming apparatus according to 1st Embodiment. It is a figure which shows the relationship between the usage-amount of a photoconductor and the film thickness of a photoconductor according to 1st Embodiment. 5 is a flowchart showing a part of processing executed by the image forming apparatus according to the first embodiment. 1 is a block diagram showing a main hardware configuration of an image forming apparatus according to a first embodiment. It is a figure which shows the relationship between the film thickness of a photoreceptor, the temperature in an image forming apparatus, and the humidity in an image forming apparatus according to 2nd Embodiment. It is a figure which shows the table which prescribes | regulates the relationship between temperature and a predetermined range according to 3rd Embodiment. It is a figure which shows the table which prescribes | regulates the relationship between temperature, a predetermined range, and predetermined time according to 4th Embodiment. It is a figure which shows the table which prescribes | regulates the relationship between a temperature range, a predetermined range, a humidity range, and predetermined time according to 5th Embodiment. 14 is a flowchart representing a part of processing executed by an image forming apparatus according to a sixth embodiment. It is a figure which shows the table which prescribes | regulates the relationship between temperature and a predetermined number of sheets according to 7th Embodiment. It is a figure which shows the table which prescribes | regulates the correlation of the charging current and the film thickness of a photoreceptor for every temperature and humidity according to 8th Embodiment.

  Embodiments according to the present invention will be described below with reference to the drawings. In the following description, the same parts and components are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated. Each embodiment and each modified example described below may be selectively combined as appropriate.

<First Embodiment>
[Image forming apparatus 100]
An image forming apparatus 100 according to the present embodiment will be described with reference to FIG. FIG. 1 is a diagram illustrating an example of the internal structure of the image forming apparatus 100.

  FIG. 1 shows an image forming apparatus 100 as a color printer. Hereinafter, the image forming apparatus 100 as a color printer will be described, but the image forming apparatus 100 is not limited to a color printer. For example, the image forming apparatus 100 may be a monochrome printer, may be a fax machine, or may be a monochrome printer, a color printer, and a multifunction machine (MFP: Multi-Functional Peripheral).

  The image forming apparatus 100 includes image forming units 1Y, 1M, 1C, and 1K, toner bottles 15Y, 15M, 15C, and 15K configured to be detachable, an intermediate transfer belt 30, a primary transfer roller 31, and a secondary transfer roller 30. A transfer roller 33, a cassette 37, a driven roller 38, a driving roller 39, a timing roller 40, a cleaning device 42, a fixing device 50, and a control device 101 are provided.

  The image forming unit 1 </ b> Y receives toner from the toner bottle 15 </ b> Y and forms a yellow (Y) toner image on the photoreceptor 10. The image forming unit 1M receives toner from the toner bottle 15M and forms a magenta (M) toner image on the photoconductor 10. The image forming unit 1 </ b> C receives the supply of toner from the toner bottle 15 </ b> C and forms a cyan (C) toner image on the photoreceptor 10. The image forming unit 1K receives toner from the toner bottle 15K and forms a black (BK) toner image on the photoconductor 10.

  The image forming units 1Y, 1M, 1C, and 1K are arranged along the intermediate transfer belt 30 in the rotation direction of the intermediate transfer belt 30, respectively. Each of the image forming units 1Y, 1M, 1C, and 1K includes a photosensitive member 10, a charging device 11, an exposure device 13, a developing device 14, and a cleaning device 17 that are configured to be rotatable.

  The charging device 11 includes a rotatable charging roller 12. The charging roller 12 is in contact with the photoconductor 10. The charging roller 12 uniformly charges the surface of the photoconductor 10 to a predetermined potential.

  The exposure device 13 irradiates the photoconductor 10 with laser light in accordance with a control signal from the control device 101, and exposes the surface of the photoconductor 10 according to the input image pattern. Thereby, an electrostatic latent image corresponding to the input image is formed on the photoreceptor 10.

  The developing device 14 develops the electrostatic latent image formed on the photoconductor 10 as a toner image. More specifically, the developing device 14 applies a developing bias to the developing roller 15 while rotating the developing roller 15, and causes the toner to adhere to the surface of the developing roller 15. The toner is transferred from the developing roller 15 to the photoconductor 10, and a toner image corresponding to the electrostatic latent image is developed on the surface of the photoconductor 10.

  The photoconductor 10 and the intermediate transfer belt 30 are in contact with each other at a portion where the primary transfer roller 31 is provided. A transfer voltage having a polarity opposite to that of the toner image is applied to the primary transfer roller 31, whereby the toner image is transferred from the photoreceptor 10 to the intermediate transfer belt 30. A yellow (Y) toner image, a magenta (M) toner image, a cyan (C) toner image, and a black (BK) toner image are sequentially superimposed and transferred from the photoreceptor 10 to the intermediate transfer belt 30. As a result, a color toner image is formed on the intermediate transfer belt 30.

  The intermediate transfer belt 30 is stretched around a driven roller 38 and a driving roller 39. The drive roller 39 is connected to a motor (not shown). When the control device 101 controls the motor, the driving roller 39 rotates. The intermediate transfer belt 30 and the driven roller 38 rotate in conjunction with the driving roller 39. As a result, the toner image on the intermediate transfer belt 30 is sent to the secondary transfer roller 33.

  The cleaning device 17 collects toner remaining on the surface of the photoconductor 10 after the transfer of the toner image from the photoconductor 10 to the intermediate transfer belt 30.

  A sheet S is set in the cassette 37. The sheets S are sent one by one from the cassette 37 to the secondary transfer roller 33 along the transport path 41 by the timing roller 40. The control device 101 controls the transfer voltage applied to the secondary transfer roller 33 in accordance with the timing at which the paper S is sent out.

  The secondary transfer roller 33 applies a transfer voltage having a polarity opposite to that of the toner image to the sheet S being conveyed. As a result, the toner image is attracted from the intermediate transfer belt 30 to the secondary transfer roller 33, and the toner image on the intermediate transfer belt 30 is transferred. The conveyance timing of the sheet S to the secondary transfer roller 33 is controlled by the timing roller 40 in accordance with the position of the toner image on the intermediate transfer belt 30. As a result, the toner image on the intermediate transfer belt 30 is transferred to an appropriate position on the paper S.

  The fixing device 50 pressurizes and heats the paper S passing through the fixing device 50. As a result, the toner image is fixed on the paper S. Thereafter, the sheet S is discharged to the tray 48.

  The cleaning device 42 collects toner remaining on the surface of the intermediate transfer belt 30 after the transfer of the toner image from the intermediate transfer belt 30 to the paper S. The collected toner is conveyed by a conveying screw (not shown) and stored in a waste toner container (not shown).

[Method for Estimating Film Thickness of Photoreceptor 10]
A method for estimating the film thickness of the photoreceptor 10 will be described with reference to FIGS.

  2 and 3 are diagrams illustrating an example of a configuration necessary for estimating the film thickness of the photoconductor 10. FIG. 2 and 3, the photoconductor 10 and the charging roller 12 are shown from different directions.

  As shown in FIGS. 2 and 3, the photoconductor 10 is in contact with the charging roller 12. Inside the photoconductor 10, a conductive cored bar 10A is provided. The cored bar 10A is connected to the ground G. Inside the charging roller 12, a conductive metal core 12A is provided. A power source 52, a current detection unit 53, and a ground G are connected in series to the core metal 12A.

  For example, the power source 52 supplies the charging roller 12 with a voltage obtained by superimposing an alternating current (AC) voltage on a direct current (DC) voltage. When a voltage is applied from the power source 52 to the charging roller 12, a potential difference is generated between the cored bar 12 </ b> A of the charging roller 12 and the cored bar 10 </ b> A of the photoreceptor 10. As a result, a discharge occurs between the charging roller 12 and the photoconductor 10, and a charging current flows through the charging roller 12 and the photoconductor 10. The charging current flows from the power source 52 → the current detection unit 53 → the charging roller 12 → the photoconductor 10 → the ground G.

  The current detection unit 53 is, for example, a current sensor for detecting the value of the current flowing through itself. The current detection unit 53 detects the value of the current flowing through the photoreceptor 10 or the charging roller 12 by applying a voltage to the charging roller 12. The detected charging current value is output to the control device 101.

  The control device 101 estimates the film thickness of the photoconductor 10 with reference to the correlation 124 that defines the relationship between the charging current value and the film thickness of the photoconductor 10. FIG. 4 is a diagram illustrating an example of the correlation 124. As shown in FIG. 4, the correlation 124 defines the film thickness of the photoconductor 10 with respect to the charging current value. The correlation 124 may be represented by a table that defines the film thickness for each charging current range, or may be represented by a relational expression having the charging current value as an explanatory variable and the film thickness as an objective variable. Good. The control device 101 refers to the correlation 124, specifies the film thickness corresponding to the value of the charging current detected by the current detection unit 53, and estimates the film thickness as the current film thickness of the photoconductor 10.

  The value of the charging current used for the estimation of the film thickness varies depending on the environment such as temperature and humidity. In an environment where the charging current is not stable, the film thickness of the photoconductor 10 output as an estimation result changes even though the film thickness itself has not actually changed. Therefore, image forming apparatus 100 according to the present embodiment estimates the film thickness of photoconductor 10 based on the charging current detected in a stable environment.

  More specifically, the image forming apparatus 100 is provided with an acquisition unit 110 for acquiring an environmental value representing an environmental state in the apparatus. The environmental value is represented by, for example, the temperature in the image forming apparatus 100, the humidity in the image forming apparatus 100, the atmospheric pressure at the installation location of the image forming apparatus 100, or other indicators that affect the charging current. The acquisition unit 110 periodically acquires an environmental value and outputs the acquired environmental value to the control device 101.

  The control device 101 acquires the charging current from the current detection unit 53 when the state where the environmental value acquired by the acquisition unit 110 is within a predetermined range continues for a predetermined time or longer. The control device 101 estimates the film thickness of the photoconductor 10 based on the acquired charging current. By estimating the film thickness of the photoconductor 10 based on the charging current detected under a stable environment, the film thickness of the photoconductor 10 is accurately estimated. As a result, it is not necessary to estimate the film thickness of the photoreceptor 10 many times, and the number of film thickness estimation processes can be reduced. Thereby, unnecessary rotation of the photoconductor 10 can be suppressed, and consumption of the photoconductor 10 is suppressed.

  The charging current detection timing will be described in more detail with reference to FIG. FIG. 5 is a diagram illustrating an example of the transition of the environmental value acquired by the acquisition unit 110.

  The image forming apparatus 100 is set with a predetermined range Δc indicating a standard where the environment is stable. The predetermined range Δc may be set in advance at the time of design or the like, or may be arbitrarily set by a service person or the like. The predetermined range Δc is defined by at least one of the lower limit value c1 and the upper limit value c2. That is, the predetermined range Δc may be defined only by the lower limit value c1, may be defined only by the upper limit value c2, or may be defined by both the lower limit value c1 and the upper limit value c2.

  Assume that the environmental value exceeds the lower limit c1 at time t1. At this time, the control device 101 starts measuring time.

  It is assumed that the environmental value falls below the lower limit value c1 at time t2. At this time, the control device 101 stops measuring time. The control device 101 determines whether the time ΔtA obtained as a measurement result has continued for a predetermined time th or more. That is, the control device 101 determines whether or not the state where the environmental value is within the predetermined range Δc has continued for the predetermined time th or more. The predetermined time th may be set in advance or may be arbitrarily set by a service person or the like.

  In the example of FIG. 5, since the time ΔtA is shorter than the predetermined time th, the control device 101 determines that the state where the environmental value is within the predetermined range Δc has not continued for the predetermined time th or more. In this case, the control apparatus 101 determines that the environment in the image forming apparatus 100 is not stable, and does not detect the charging current.

  It is assumed that the state where the environmental value is within the predetermined range Δc continues at the time t4 for the predetermined time th or more. At this time, the control device 101 determines that the environment in the image forming apparatus 100 is stable, and outputs a command for detecting the charging current to the current detection unit 53. Thereby, the charging current is detected in a stable environment. The control device 101 estimates the film thickness of the photoconductor 10 based on the charging current detected in a stable environment.

  The detection timing of the charging current used for the film thickness estimation processing is not limited to the timing at which the state where the environmental value is within the predetermined range Δc continues for the predetermined time th (that is, time t4), and from time t4 to time It may be detected during t5. That is, after the state where the environmental value is within the predetermined range Δc continues for a predetermined time th or more and the environmental value is within the predetermined range Δc, the charging current used for the film thickness estimation process is It can be detected at any timing.

  Further, since the charging current detected in a stable environment may be used for the film thickness estimation process, the estimation process is executed at an arbitrary timing after the charging current is detected. That is, the film thickness estimation process is executed at an arbitrary timing after time t4.

[Functional Configuration of Image Forming Apparatus 100]
The function of the image forming apparatus 100 will be described with reference to FIGS.

  FIG. 6 is a diagram illustrating an example of a functional configuration of the image forming apparatus 100. As illustrated in FIG. 6, the control device 101 of the image forming apparatus 100 includes an environment determination unit 150, a film thickness estimation unit 152, a life determination unit 154, and a life prediction unit 156 as functional configurations.

  The environment determination unit 150 determines whether or not the state in which the environment value output from the acquisition unit 110 (see FIGS. 2 and 3) is within a predetermined range continues for a predetermined time or more. When the environment determination unit 150 determines that the state where the environment value is within the predetermined range has continued for a predetermined time or more, the stability condition indicating that the environment in the image forming apparatus 100 is stable is satisfied. Judge that it was done.

  When it is determined by the environment determination unit 150 that the stability condition is satisfied, the film thickness estimation unit 152 outputs a current detection command to the current detection unit 53 (see FIGS. 2 and 3), and the current detection unit 53 The value of the charging current is obtained from The film thickness estimation unit 152 estimates the film thickness of the photoconductor 10 based on the acquired charging current value. The method for estimating the film thickness is as described with reference to FIG. 4, and therefore the description thereof will not be repeated. The estimated film thickness is output to each of the life determination unit 154 and the life prediction unit 156.

  The life determination unit 154 determines whether or not the film thickness estimated by the film thickness estimation unit 152 is less than a predetermined value. The life determination unit 154 determines that the life of the photoconductor 10 has reached when the estimated film thickness is less than a predetermined value. By using the accurately estimated film thickness for determining the lifetime of the photoconductor 10, the lifetime determining unit 154 can accurately determine whether or not the lifetime of the photoconductor 10 has been reached.

  When the life determination unit 154 determines that the life of the photoconductor 10 has come, it outputs that as a warning. This warning is notified to, for example, a user or a service person. The notification is realized by sending a warning mail, displaying a warning screen, outputting a warning sound, or the like. By notifying that the life of the photoconductor 10 has come, a user or a service person can grasp that the photoconductor 10 needs to be replaced.

  The lifetime predicting unit 156 calculates the rate of decrease in the film thickness of the photoconductor 10 based on the amount of change in the film thickness of the photoconductor 10 and the usage amount of the photoconductor 10 at the time of estimation of the film thickness. Based on the above, the lifetime of the photoreceptor 10 is predicted. Below, with reference to FIG. 7, the function of the lifetime estimation part 156 is demonstrated.

  FIG. 7 is a diagram showing the relationship between the usage amount of the photoconductor 10 and the film thickness of the photoconductor 10. FIG. 7 shows a graph 60. The horizontal axis of the graph 60 represents the usage amount of the photoreceptor 10. The amount of use of the photoconductor 10 is represented by the number of rotations of the photoconductor 10 up to the present, the use time up to the present (rotation time), and the like. The vertical axis of the graph 60 represents the film thickness of the photoreceptor 10.

A point P0 on the graph 60 indicates the initial film thickness of the photoconductor 10 when the photoconductor 10 is not used (for example, when the photoconductor 10 is replaced). The point P0 is represented by a usage amount “x ₀ ” and an initial film thickness “y ₀ ”. Typically, the usage amount “x ₀ ” at the point P ₀ is “0”. The initial film thickness “y ₀ ” may be set in advance or may be estimated by the film thickness estimation unit 152 when not used. Points P 1 and P 2 on the graph 60 indicate the film thickness of the photoconductor 10 estimated by the film thickness estimation unit 152. The point P1 is represented by the usage amount “x ₁ ” and the film thickness “y ₁ ”. The point P2 is represented by the usage amount “x ₂ ” and the film thickness “y ₂ ”.

  The life prediction unit 156 calculates the transition of the film thickness of the photoconductor 10 from at least two points P0 to P2. For example, when the points P0 and P1 are known, the transition of the film thickness is calculated by the linear equation of the following formula (1).

y−y ₀ = (y ₁ −y ₀ ) / (x ₁ −x ₀ ) · (x−x ₁ ) (1)
“Y ₁ -y ₀ ” shown in Equation (1) represents the amount of change in film thickness. “(Y ₁ −y ₀ ) / (x ₁ −x ₀ )” in the equation (1) represents a decrease amount of the film thickness per predetermined usage (that is, a decrease rate of the film thickness), and the slope of the graph 60 It corresponds to.

  When the points P1 and P2 are known, the transition of the film thickness is calculated by the linear equation of the following equation (2).

y−y ₁ = (y ₂ −y ₁ ) / (x ₂ −x ₁ ) · (x−x ₂ ) (2)
“Y ₂ −y ₁ ” shown in Expression (2) represents the amount of change in film thickness. “(Y ₂ −y ₁ ) / (x ₂ −x ₁ )” in the expression (2) represents a decrease amount of the film thickness per predetermined use amount (that is, a decrease rate of the film thickness), and the slope of the graph 60 It corresponds to.

The lifetime predicting unit 156 calculates “x = X _th ” by substituting the film thickness “Y _th ” indicating the lifetime of the photoconductor 10 into “y” in Equation (1) or Equation (2). The calculated “X _th ” represents the usage amount at which the lifetime of the photoconductor 10 comes. The remaining usable amount is calculated by calculating the usage amount “X _th ” that reaches the end of its life. Thereby, the lifetime of the photoreceptor 10 is predicted. By predicting the lifetime of the photoreceptor 10 from the accurately estimated film thickness, the image forming apparatus 100 can also accurately predict the lifetime of the photoreceptor 10.

  The predicted life is notified to the user or service person. By notifying the life of the photoconductor 10, the user or service person can accurately grasp the replacement time of the photoconductor 10.

  Preferably, the life prediction unit 156 predicts the timing when the life of the photoconductor 10 comes. As an example, the lifetime predicting unit 156 calculates the timing when the lifetime of the photoconductor 10 comes by dividing the remaining usable amount of the photoconductor 10 by the usage pace (usage speed). The usage pace is obtained from the usage history of the photoconductor 10 or the like.

  More preferably, the life prediction unit 156 calculates the consumption rate of the photoconductor 10. The consumption rate is calculated by the following equation (3), for example.

m = v · X / (y ₀ −Yth) · 100 (3)
“M” shown in Expression (3) represents the consumption rate of the photoreceptor 10. “V” represents a reduction rate of the film thickness of the photoreceptor 10. “X” represents the usage amount of the photoconductor 10 from when the photoconductor 10 is not used to the present time. “Y ₀ ” represents the film thickness of the photoreceptor 10 when not in use. “Y _th ” represents a film thickness serving as a reference for the life of the photoreceptor 10.

  In the above description, the example in which the film thickness transition of the photoconductor 10 is calculated based on the points P0 and P1 or the points P1 and P2 has been described. However, the point P0 and the average of the points P1 and P2 are described. Based on this, the transition of the film thickness of the photoconductor 10 may be calculated. The life prediction unit 156 can predict the life of the photoconductor 10 more accurately by using an average of the estimated plurality of film thicknesses.

  In the above description, the example in which the change in the film thickness of the photoconductor 10 is calculated by a linear equation has been described. However, the change in the film thickness of the photoconductor 10 may be calculated by another approximate expression.

  In the above description, an example in which the estimated film thickness is used for determining the life of the photoreceptor 10 has been described. However, the estimated film thickness may be used for other purposes. For example, the estimated film thickness is collected from various image forming apparatuses 100 and converted into a database. At this time, the estimated film thickness is associated with environmental values such as temperature and humidity and is converted into a database, so that the designer can analyze the cause of the wear of the photoreceptor 10. The designer can improve the photoreceptor 10 based on the knowledge obtained as an analysis result.

[Control Structure of Image Forming Apparatus 100]
A control structure of the image forming apparatus 100 will be described with reference to FIG. FIG. 8 is a flowchart showing a part of processing executed by image forming apparatus 100. The processing in FIG. 8 is realized by the control device 101 of the image forming apparatus 100 executing a program. In other aspects, some or all of the processing may be performed by circuit elements or other hardware.

  In step S <b> 110, the control apparatus 101 acquires an environmental value representing an environmental state in the image forming apparatus 100 from the acquisition unit 110 (see FIGS. 2 and 3). The environmental value is represented by, for example, the temperature in the image forming apparatus 100, the humidity in the image forming apparatus 100, the atmospheric pressure at the installation location of the image forming apparatus 100, or other indicators that affect the charging current.

  In step S120, the control device 101 determines, as the above-described environment determination unit 150 (see FIG. 6), whether or not the state in which the environment value acquired in step S110 is within a predetermined range continues for a predetermined time or more. .

  In one aspect, the control device 101 starts measuring time based on the environmental value falling within the predetermined range, and continues measuring the time while the environmental value falls within the predetermined range. When the environmental value is out of the predetermined range, the measurement of the time is stopped and the measured time is reset. When the measured time exceeds a predetermined time, the control device 101 determines that the state where the environmental value is within the predetermined range continues for a predetermined time or more.

  In another aspect, the control device 101 is in a state where the environmental value is within the predetermined range when the environmental value acquired in step S110 and the environmental value detected within the past predetermined time are within the predetermined range. Is determined to have continued for a predetermined time or more.

  When control device 101 determines that the state where the environmental value is within the predetermined range continues for a predetermined time or longer (YES in step S120), control device 101 switches control to step S140. If not (NO in step S120), control device 101 returns control to step S110.

  In step S140, the control apparatus 101 outputs a current detection command to the current detection unit 53 (see FIGS. 2 and 3) as the above-described film thickness estimation unit 152 (see FIG. 6). Get the value. The film thickness estimation unit 152 estimates the film thickness of the photoconductor 10 based on the acquired charging current value. Since the method for estimating the film thickness is as described with reference to FIG. 4, the description thereof will not be repeated.

  In step S150, the control apparatus 101 determines whether the film thickness estimated in step S140 is below a predetermined value as the above-described life determination unit 154 (see FIG. 6). When control apparatus 101 determines that the film thickness estimated in step S140 is below a predetermined value (YES in step S150), control apparatus 101 switches control to step S152. If not (NO in step S150), control device 101 switches control to step S154.

  In step S <b> 152, the control device 101 notifies that the life of the photoconductor 10 has come. The notification is realized by sending a warning mail, displaying a warning screen, outputting sound, or the like.

  In step S154, the control apparatus 101 serves as the above-described life prediction unit 156 (see FIG. 6) based on the amount of change in the film thickness of the photoconductor 10 and the amount of use of the photoconductor 10 at the estimated time of the film thickness. The reduction rate of the film thickness of the photoconductor 10 is calculated, and the lifetime of the photoconductor 10 is predicted based on the reduction rate. Since the method for predicting the lifetime of the photoreceptor is as described with reference to FIG. 7, the description thereof will not be repeated. The control device 101 outputs the predicted lifetime of the photoreceptor 10. The output destination of the lifetime is arbitrary. As an example, the said lifetime is transmitted to the portable terminal for service persons. The portable terminal displays the life received from the image forming apparatus 100 on the screen. Thereby, the service person can grasp the replacement time of the photoconductor 10.

[Hardware Configuration of Image Forming Apparatus 100]
With reference to FIG. 9, an example of a hardware configuration of the image forming apparatus 100 will be described. FIG. 9 is a block diagram illustrating a main hardware configuration of the image forming apparatus 100.

  As illustrated in FIG. 9, the image forming apparatus 100 includes a control device 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, a communication interface 104, an operation panel 105, and an acquisition unit 110. And a storage device 120.

  The control device 101 is configured by at least one integrated circuit, for example. The integrated circuit includes, for example, at least one CPU (Central Processing Unit), at least one ASIC (Application Specific Integrated Circuit), at least one FPGA (Field Programmable Gate Array), or a combination thereof.

  The control device 101 controls the operation of the image forming apparatus 100 by executing various programs such as a program 122 for estimating the film thickness of the photoconductor 10. The control device 101 reads the program 122 from the storage device 120 to the ROM 102 based on receiving the execution instruction of the program 122. The RAM 103 functions as a working memory and temporarily stores various data necessary for executing the program 122.

  An antenna (not shown) or the like is connected to the communication interface 104. The image forming apparatus 100 exchanges data with an external communication device via an antenna. The external communication device includes, for example, a mobile communication terminal such as a smartphone, a server, and the like. The image forming apparatus 100 may be configured to download the program 122 from a server via an antenna.

  The operation panel 105 includes a display and a touch panel. The display and the touch panel are overlapped with each other, and the operation panel 105 receives, for example, an input of a setting value for estimating the film thickness of the photoreceptor 10. For example, the operation panel 105 receives the setting of the predetermined range Δc (see FIG. 5) and the predetermined time th (see FIG. 5). Further, the operation panel 105 displays a warning screen for warning that the life of the photoconductor 10 has reached, a timing when the life of the photoconductor 10 has come, and the like.

  The acquisition unit 110 acquires an environmental value representing an environmental state in the image forming apparatus 100. For example, the acquisition unit 110 includes a temperature sensor 107 for detecting the temperature in the image forming apparatus 100 as an environmental value. The acquisition unit 110 includes a humidity sensor 108 for detecting the humidity (relative humidity or absolute humidity) in the image forming apparatus 100 as an environmental value. The temperature sensor 107 and the humidity sensor 108 may be integrally configured as a temperature / humidity sensor or may be configured separately. In addition, the acquisition unit 110 may include an atmospheric pressure sensor for detecting the atmospheric pressure at the installation location of the image forming apparatus 100 as an environmental value, a sensor for detecting other indicators that affect the charging current, and the like. Good.

  The storage device 120 is a storage medium such as a hard disk or an external storage device. Storage device 120 stores program 122 according to the present embodiment, correlation 124 described above (see FIG. 4), and the like. The storage location of the program 122 and the correlation 124 is not limited to the storage device 120. The program 122 and the correlation 124 are stored in the storage area (for example, a cache) of the control device 101, the ROM 102, the RAM 103, and an external device (for example, a server). Or the like.

  The program 122 may be provided by being incorporated in a part of an arbitrary program, not as a single program. In this case, the control process according to the present embodiment is realized in cooperation with an arbitrary program. Even such a program that does not include some modules does not depart from the spirit of the program 122 according to the present embodiment. Furthermore, some or all of the functions provided by the program 122 may be realized by dedicated hardware. Furthermore, the image forming apparatus 100 may be configured in a form such as a so-called cloud service in which at least one server executes part of the processing of the program 122.

[Summary of First Embodiment]
As described above, image forming apparatus 100 according to the present embodiment detects charging current when the environmental value is within a predetermined range for a predetermined time or longer, and performs photosensitivity based on the charging current. The film thickness of the body 10 is estimated. The film thickness of the photoconductor 10 is accurately estimated by estimating the film thickness of the photoconductor 10 based on the charging current detected in a situation where the environment is stable. As a result, it is not necessary to estimate the film thickness of the photoreceptor 10 many times, and the number of film thickness estimation processes can be reduced. Thereby, the image forming apparatus 100 can suppress unnecessary rotation of the photoconductor 10, and consumption of the photoconductor 10 is suppressed.

<Second Embodiment>
[Overview]
Image forming apparatus 100 according to the first embodiment estimates the film thickness of photoconductor 10 based on the charging current. In contrast, the image forming apparatus 100 according to the second embodiment estimates the film thickness of the photoconductor 10 based on not only the charging current but also the temperature and humidity in the image forming apparatus 100.

  Since the other points are the same as those of image forming apparatus 100 according to the first embodiment, description thereof will not be repeated below.

[Method for Estimating Film Thickness of Photoreceptor 10]
With reference to FIG. 10, a method of estimating the film thickness of the photoconductor 10 in the second embodiment will be described.

  FIG. 10 is a diagram illustrating the relationship among the film thickness of the photoconductor 10, the temperature in the image forming apparatus 100, and the humidity in the image forming apparatus 100. As shown in FIG. 10, the charging current fluctuates in response to changes in temperature and humidity. Therefore, there is a possibility that the charging current changes under an environment where the temperature and humidity change, and the film thickness of the photoconductor 10 cannot be estimated accurately. Therefore, the control device 101 of the image forming apparatus 100 detects the value of the charging current detected by the current detection unit 53 (see FIGS. 2 and 3), the temperature detected by the temperature sensor 107 (see FIG. 9), and the humidity. Based on the humidity detected by the sensor 108 (see FIG. 9), the film thickness of the photoconductor 10 is estimated. Thereby, the film thickness of the photoconductor 10 is estimated more accurately.

  As an example, a correlation between charging current, temperature, humidity, and film thickness is defined in advance by experiments or the like. The correlation may be represented by a table that defines the film thickness for each charging current range, for each temperature range, and for each humidity range, or the charging current, temperature, and humidity are explanatory variables. It may be expressed by a relational expression as an objective variable. The control device 101 refers to the correlation, identifies the film thickness corresponding to the detected charging current, temperature, and humidity, and estimates the film thickness as the current film thickness of the photoconductor 10.

  In the above description, the example in which the film thickness of the photoconductor 10 is estimated based on the correlation among the charging current, temperature, humidity, and film thickness has been described. However, the correlation between the charging current, temperature, and film thickness. The film thickness of the photoconductor 10 may be estimated based on the above, or the film thickness of the photoconductor 10 may be estimated based on the correlation among the charging current, the humidity, and the film thickness. That is, it is not necessary to use both temperature and humidity for estimating the film thickness of the photoreceptor 10.

[Summary of Second Embodiment]
As described above, image forming apparatus 100 according to the present embodiment uses not only the charging current but also the temperature in image forming apparatus 100 and the humidity in image forming apparatus 100 to further form the film of photoconductor 10. Estimate the thickness. Thereby, the film thickness of the photoconductor 10 is estimated more accurately.

<Third Embodiment>
[Overview]
As described above, in the image forming apparatus 100, the environment in the image forming apparatus 100 is stable when the environmental value such as the temperature is within the predetermined range Δc (see FIG. 5) for a predetermined time. Judge. At this time, in the first embodiment, the predetermined range Δc is constant. However, as shown in FIG. 10 described above, the charging current is more likely to change as the temperature in the image forming apparatus 100 is lower. Therefore, the reliability of the charging current is lower in a low temperature environment. Therefore, image forming apparatus 100 according to the third embodiment narrows predetermined range Δc as the temperature inside the apparatus decreases. Thus, the lower the temperature in the image forming apparatus 100, the stricter the conditions for determining whether the environment is stable. As a result, the image forming apparatus 100 can accurately estimate the film thickness of the photoreceptor 10 even in a low temperature environment.

  Since other points are the same as those of image forming apparatus 100 according to the first and second embodiments, description thereof will not be repeated below.

[Method for Determining Predetermined Range Δc]
With reference to FIG. 11, a method for determining the predetermined range Δc of the environmental value indicating the standard where the environment is stable will be described.

  FIG. 11 is a diagram showing a table 126 that defines the relationship between the temperature and the predetermined range Δc. In the table 126, a predetermined range Δc is associated with each temperature range. In the example of the table 126 of FIG. 11, the predetermined range Δc is narrowed as the temperature is lower. The table 126 is stored in advance in, for example, the storage device 120 (see FIG. 9) of the image forming apparatus 100, an external device (for example, a server), or other storage medium.

  The control device 101 of the image forming apparatus 100 acquires the temperature from the temperature sensor 107 (see FIG. 9) based on the arrival of the timing for determining whether the environment inside the apparatus is stable. The control device 101 refers to the table 126 and specifies a predetermined range Δc corresponding to the detected temperature. Thereafter, the control device 101 determines whether or not the temperature detected from a predetermined time before to the present time is within the specified range Δc. When the control device 101 determines that the temperature detected from the predetermined time before to the present time is within the specified range Δc, the control device 101 determines that the environment in the image forming apparatus 100 is stable, A command for detecting the charging current is output to the current detector 53 (see FIGS. 2 and 3). Thereby, the charging current is detected in a stable environment. The control device 101 estimates the film thickness of the photoconductor 10 based on the charging current detected in a stable environment.

  The numerical values in the table 126 shown in FIG. 11 are examples, and arbitrary numerical values can be set in the table 126.

  In the example of FIG. 11, the relationship between the temperature and the predetermined range Δc is defined as the table 126, but the relationship between the temperature and the predetermined range Δc may be represented by a relational expression. In the relational expression, the temperature is expressed as an explanatory variable, and the predetermined range Δc is expressed as an objective variable.

[Summary of Third Embodiment]
As described above, image forming apparatus 100 according to the present embodiment narrows predetermined range Δc as the temperature inside the apparatus decreases. Thus, the lower the temperature in the image forming apparatus 100, the stricter the conditions for determining whether the environment is stable. As a result, the image forming apparatus 100 can accurately detect the charging current even in a low temperature environment, and can accurately estimate the film thickness of the photoconductor 10.

<Fourth embodiment>
[Overview]
As described above, in the image forming apparatus 100, when the environmental value such as the temperature is within the predetermined range Δc (see FIG. 5) for a predetermined time th (see FIG. 5) or longer, the environment inside the apparatus is Judge that it is stable. At this time, in the first embodiment, the predetermined time th is constant. In contrast, image forming apparatus 100 according to the fourth embodiment adjusts predetermined time th according to the temperature inside the apparatus.

  Since other points are the same as those of image forming apparatus 100 according to the first to third embodiments, description thereof will not be repeated below.

[Method for determining the predetermined time th]
A method for determining the predetermined time th will be described with reference to FIG.

  FIG. 12 is a diagram showing a table 126A that defines the relationship among the temperature, the predetermined range Δc, and the predetermined time th. In the table 126A, a predetermined range Δc and a predetermined time th are associated with each temperature range. In the example of the table 126A in FIG. 12, the predetermined time th is longer as the temperature is lower. The table 126A is stored in advance in, for example, the storage device 120 (see FIG. 9) of the image forming apparatus 100, an external device (for example, a server), or other storage medium.

  The control device 101 of the image forming apparatus 100 acquires the temperature from the temperature sensor 107 (see FIG. 9) based on the arrival of the timing for determining whether the environment inside the apparatus is stable. The control device 101 refers to the table 126A and specifies a predetermined range Δc corresponding to the detected temperature and a predetermined time th. Thereafter, the control device 101 determines whether or not the temperature detected from the predetermined time th to the present time is within the predetermined range Δc. If the control device 101 determines that the temperature detected from the predetermined time th to the present time is within the predetermined range Δc, the control device 101 determines that the environment in the image forming apparatus 100 is stable, and the charging current. Is output to the current detector 53 (see FIGS. 2 and 3). Thereby, the charging current is detected in a stable environment. The control device 101 estimates the film thickness of the photoconductor 10 based on the charging current detected in a stable environment.

  In FIG. 12, an example in which the predetermined time th is changed for each temperature has been described, but the predetermined time th may be constant.

  Also, the numerical values in the table 126A shown in FIG. 12 are examples, and arbitrary numerical values can be set in the table 126A.

[Summary of Fourth Embodiment]
As described above, image forming apparatus 100 according to the present embodiment adjusts predetermined time th according to the temperature inside the apparatus. Accordingly, a condition indicating whether or not the environment is stable is set for each temperature, so that the image forming apparatus 100 can detect the charging current in a more stable environment. As a result, the image forming apparatus 100 can estimate the film thickness of the photoconductor 10 more accurately.

<Fifth embodiment>
[Overview]
In the first embodiment, an example in which temperature is used as an index for determining whether or not the environment is stable has been mainly described. On the other hand, image forming apparatus 100 according to the fifth embodiment determines whether or not the environment is stable by using not only temperature but also humidity.

  Since other points are the same as those of image forming apparatus 100 according to the first to fourth embodiments, description thereof will not be repeated below.

[How to judge whether the environment is stable]
A method for determining whether or not the environment is stable will be described with reference to FIG.

  FIG. 13 is a diagram showing a table 126B that defines the relationship among the temperature range, the predetermined range Δc, the humidity range Δd, and the predetermined time th. The table 126B is stored in advance in, for example, the storage device 120 (see FIG. 9) of the image forming apparatus 100, an external device (for example, a server), or other storage medium.

  The control device 101 of the image forming apparatus 100 acquires the temperature from the temperature sensor 107 (see FIG. 9) based on the arrival of the timing for determining whether the environment inside the apparatus is stable. The control device 101 refers to the table 126B and specifies a predetermined range Δc, a humidity range Δd, and a predetermined time th corresponding to the detected temperature. Thereafter, the control device 101 determines whether or not the temperature detected by the temperature sensor 107 is within the predetermined range Δc between the predetermined time th and the present, and between the predetermined time th and the present. Next, it is determined whether the humidity detected by the humidity sensor 108 (see FIG. 9) is within a predetermined range Δd. The control device 101 determines that the temperature detected by the temperature sensor 107 is within the predetermined range Δc between the predetermined time th and the present, and the humidity sensor 108 between the predetermined time th and the present. If it is determined that the humidity detected by the above is within the predetermined range Δd, it is determined that the environment in the image forming apparatus 100 is stable. In this case, the control device 101 outputs a command for detecting the charging current to the current detection unit 53 (see FIGS. 2 and 3). Thereby, the charging current is detected in a more stable environment. The control device 101 estimates the film thickness of the photoconductor 10 based on the charging current detected in a stable environment.

[Summary of Fifth Embodiment]
As described above, image forming apparatus 100 according to the present embodiment further uses not only temperature but also humidity as an index for determining whether or not the environment inside the apparatus is stable. Accordingly, the image forming apparatus 100 can more accurately determine whether or not the environment inside the apparatus is stable, and can detect the charging current in a more stable environment. As a result, the image forming apparatus 100 can estimate the film thickness of the photoconductor 10 more accurately.

<Sixth Embodiment>
[Overview]
The image forming apparatus 100 according to the first embodiment determines that the environment inside the apparatus is stable when the state where the environmental value such as the temperature is within a predetermined range continues for a predetermined time or longer. In contrast, the image forming apparatus 100 according to the sixth embodiment uses not only the environmental value but also the number of printed sheets in the past predetermined time as an index for determining whether or not the internal environment of the apparatus is stable. Further use. By adding a condition for determining whether or not the environment is stable, the charging current can be detected in a more stable environment.

  Since other points are the same as those of image forming apparatus 100 according to the first to fifth embodiments, description thereof will not be repeated below.

[Control Structure of Image Forming Apparatus 100]
A control structure of image forming apparatus 100 according to the sixth embodiment will be described with reference to FIG. FIG. 14 is a flowchart representing a part of processing executed by image forming apparatus 100 according to the sixth embodiment. The processing in FIG. 14 is realized by the control device 101 of the image forming apparatus 100 executing a program. In other aspects, some or all of the processing may be performed by circuit elements or other hardware.

  Since processes other than steps S122 and S130 shown in FIG. 14 are the same as those described in FIG. 8, the description thereof will not be repeated.

  In step S122, the control apparatus 101 acquires the number of printed sheets within the past predetermined time. The number of prints is acquired from a print history stored in the image forming apparatus 100.

  In step S130, the control apparatus 101 determines whether or not the number of printed sheets in the past predetermined time is less than the predetermined number. If control apparatus 101 determines that the number of printed sheets in the past predetermined time is less than the predetermined number (YES in step S130), control device 101 switches control to step S140. If not (NO in step S130), control device 101 returns control to step S110.

[Summary of Sixth Embodiment]
As described above, image forming apparatus 100 according to the present embodiment not only determines whether or not the state where the environmental value is within the predetermined range continues for a predetermined time or longer (processing in step S120). It is further determined whether or not the number of printed sheets in the past predetermined time is less than the predetermined number (step S130). As described above, not only the environmental value but also the number of printed sheets in the past predetermined time is further used as an index for determining whether or not the environment inside the apparatus is stable. When the number of printed sheets in the past predetermined time is small, a charging current detection process used for the film thickness estimation process is executed.

  When the number of printed sheets in the past predetermined time is small, there is a high possibility that the environment in the image forming apparatus 100 is stable. Therefore, the charging current is detected in a more stable environment. As a result, the image forming apparatus 100 can estimate the film thickness of the photoconductor 10 more accurately.

<Seventh embodiment>
The image forming apparatus 100 according to the sixth embodiment described above determines that the environment inside the apparatus is stable when the number of printed sheets in the past predetermined time is less than the predetermined number n. At this time, in the sixth embodiment, the predetermined number n is constant. In contrast, the image forming apparatus 100 according to the seventh embodiment adjusts the predetermined number n according to the temperature inside the apparatus.

  Since other points are the same as those of image forming apparatus 100 according to the first to sixth embodiments, description thereof will not be repeated below.

[Determination method of predetermined number n]
With reference to FIG. 15, a method for determining the predetermined number n that is a criterion for a stable environment will be described.

  FIG. 15 is a diagram showing a table 126C that defines the relationship between the temperature and the predetermined number n. In the table 126C, a predetermined number n is associated with each temperature range. In the example of FIG. 15, the predetermined number n is smaller as the temperature is lower. The table 126C is stored in advance in, for example, the storage device 120 (see FIG. 9) of the image forming apparatus 100, an external device (for example, a server), or other storage medium.

  The control device 101 of the image forming apparatus 100 continues the state in which the environmental value is within a predetermined range for a predetermined time or longer based on the arrival of the timing for determining whether or not the internal environment is stable. Determine whether or not. When it is determined whether or not the state where the environmental value is within the predetermined range continues for a predetermined time or longer, the control device 101 acquires the temperature from the temperature sensor 107 (see FIG. 9). The control device 101 refers to the table 126C and specifies the predetermined number n corresponding to the detected temperature. Thereafter, the control device 101 determines whether or not the number of printed sheets in the past predetermined time is less than the specified predetermined number n. If the control device 101 determines that the number of printed sheets in the past predetermined time is less than the specified number n, the control device 101 determines that the environment inside the device is stable and detects a charging current. Is output to the current detector 53 (see FIGS. 2 and 3). Thereby, the charging current is detected in a stable environment. The control device 101 estimates the film thickness of the photoconductor 10 based on the charging current detected in a stable environment.

  Note that the numerical values in the table 126C shown in FIG. 15 are examples, and arbitrary numerical values can be set in the table 126C.

  In the example of FIG. 15, the relationship between the temperature and the predetermined number n is defined as the table 126C. However, the relationship between the temperature and the predetermined number n may be expressed by a relational expression. In the relational expression, the temperature is expressed as an explanatory variable, and the predetermined number n is expressed as an objective variable.

[Summary of seventh embodiment]
As described above, image forming apparatus 100 according to the present embodiment adjusts predetermined number n according to the temperature inside the apparatus. Accordingly, a condition indicating whether or not the environment is stable is set for each temperature, so that the image forming apparatus 100 can detect the charging current in a more stable environment. As a result, the image forming apparatus 100 can estimate the film thickness of the photoconductor 10 more accurately.

<Eighth Embodiment>
[Overview]
The image forming apparatus 100 according to the first embodiment estimates the film thickness of the photoconductor 10 based on the above-described correlation 124 (see FIG. 4) indicating the relationship between the charging current and the film thickness of the photoconductor 10. It was. At this time, in the first embodiment, the correlation 124 is constant regardless of environmental values such as temperature and humidity. On the other hand, in the eighth embodiment, the correlation 124 is prepared for each environmental value such as temperature and humidity. Accordingly, the image forming apparatus 100 can estimate the film thickness more accurately without being affected by temperature, humidity, and the like.

  Since other points are the same as those of image forming apparatus 100 according to the first to seventh embodiments, description thereof will not be repeated below.

[Thickness estimation method]
A method for estimating the film thickness of the photoreceptor 10 will be described with reference to FIG.

  FIG. 16 is a diagram showing a table 126D that defines the correlation between the charging current and the film thickness of the photoconductor 10 for each temperature and humidity. In the table 126D, the correlation between the charging current and the film thickness of the photoconductor 10 is shown as a relational expression. In the table 126D, the relational expression is defined for each temperature range and each humidity range. The table 126D is stored in advance in, for example, the storage device 120 (see FIG. 9) of the image forming apparatus 100, an external device (for example, a server), or other storage medium.

  The control device 101 of the image forming apparatus 100 acquires the temperature from the temperature sensor 107 (see FIG. 9) based on the arrival of the timing for estimating the film thickness of the photoconductor 10, and the humidity sensor 108 ( Humidity is acquired from FIG. The control device 101 refers to the table 126D and specifies a relational expression corresponding to the detected temperature and the detected humidity. Thereafter, the control device 101 calculates the film thickness of the photoconductor 10 by substituting the charging current detected in a stable environment into the specified relational expression.

  In the table 126D of FIG. 16, a relational expression between the charging current and the film thickness of the photoconductor 10 is defined for each temperature and humidity. However, the relational expression may be defined for each temperature. It may be defined for each humidity, or for each other environmental value such as atmospheric pressure.

[Summary of Eighth Embodiment]
As described above, in the present embodiment, the correlation between the charging current and the film thickness of the photoconductor 10 is defined for each environmental value such as temperature and humidity. Thereby, the image forming apparatus 100 can estimate the film thickness more accurately.

<Ninth embodiment>
Image forming apparatus 100 according to the first embodiment estimates the film thickness after the environmental value is within the predetermined range for a predetermined time or longer and if the environmental value is within the predetermined range. The charging current used for processing was detected at an arbitrary timing. In contrast, in the ninth embodiment, the charging current used for the film thickness estimation process is detected during the printing process in a stable environment.

  More specifically, the image forming apparatus 100 normally detects a charging current during printing processing and determines a charging voltage to be applied to the charging roller 12 based on the charging current. If the charging current detected in the process of determining the charging voltage is used for the estimation of the film thickness, the image forming apparatus 100 does not need to detect the charging current for the film thickness estimation process. For this reason, it is preferable that the charging current value used for the estimation of the film thickness is the one detected during the charging voltage determination process that is executed in a situation where the environment in the image forming apparatus 100 is stable. . Thereby, unnecessary rotation of the photoconductor 10 can be suppressed, and consumption of the photoconductor 10 is suppressed.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1C, 1K, 1M, 1Y Image forming unit, 10 photoconductor, 10A, 12A cored bar, 11 charging device, 12 charging roller, 13 exposure device, 14 developing device, 15 developing roller, 15C, 15K, 15M, 15Y toner bottle , 17, 42 Cleaning device, 30 Intermediate transfer belt, 31 Primary transfer roller, 33 Secondary transfer roller, 37 Cassette, 38 Drive roller, 39 Drive roller, 40 Timing roller, 41 Transport path, 48 Tray, 50 Fixing device, 52 Power supply, 53 Current detection unit, 60 graph, 100 Image forming device, 101 Control device, 102 ROM, 103 RAM, 104 Communication interface, 105 Operation panel, 107 Temperature sensor, 108 Humidity sensor, 110 Acquisition unit, 120 Storage device, 122Program, 124 correlations, 126,126A～126D table 150 environment determination section, 152 thickness estimation unit, 154 life judgment unit, 156 life prediction unit.

Claims (11)

An image forming apparatus,
A photoreceptor,
A charging roller for charging the photoreceptor;
A detection unit for detecting a value of a current flowing through the photosensitive member or the charging roller by applying a voltage to the charging roller;
An acquisition unit for acquiring an environmental value representing an environmental state in the image forming apparatus;
A control device that estimates the film thickness of the photoconductor based on the value of the current detected by the detection unit when the state where the environmental value is within a predetermined range continues for a predetermined time or more. Image forming apparatus.   The control device calculates a reduction rate of the film thickness based on the change amount of the film thickness and a usage amount of the photoconductor at the estimated time of the film thickness, and based on the decrease rate, the control unit calculates the thickness of the photoconductor. The image forming apparatus according to claim 1, wherein the lifetime is predicted.   3. The image forming apparatus according to claim 1, wherein when the estimated film thickness is less than a predetermined value, the control device outputs that the life of the photoconductor is reached.   The image forming apparatus according to claim 1, wherein the acquisition unit includes a temperature sensor for detecting a temperature in the image forming apparatus as the environmental value.   The image forming apparatus according to claim 4, wherein the acquisition unit includes a humidity sensor for detecting humidity in the image forming apparatus as the environmental value.   The image forming apparatus according to claim 5, wherein the control device estimates the film thickness based on the value of the current, the temperature, and the humidity.   The image forming apparatus according to claim 4, wherein the control device narrows the predetermined range as a temperature detected by the temperature sensor is lower.   The value of the current used for the film thickness estimation process is detected when the number of printed sheets within a predetermined time by the image forming apparatus is less than a predetermined number. The image forming apparatus described. The control device performs a determination process for determining a magnitude of a voltage to be applied to the charging roller based on a current value detected by the detection unit during a printing process by the image forming apparatus,
The image forming apparatus according to claim 1, wherein a value of the current detected by the detection unit during the determination process is used for the estimation of the film thickness. An estimation method for estimating a film thickness of a photoreceptor provided in an image forming apparatus,
Applying a voltage to a charging roller for charging the photoreceptor;
Detecting a value of a current flowing through the photosensitive member or the charging roller by applying the voltage to the charging roller;
Obtaining an environmental value representing an environmental state in the image forming apparatus;
Estimating the film thickness of the photoconductor based on the value of the current detected in the detecting step when the environmental value is within a predetermined range for a predetermined time or longer. Estimation method. An estimation program for estimating a film thickness of a photoreceptor provided in an image forming apparatus,
The estimation program is stored in the image forming apparatus.
Applying a voltage to a charging roller for charging the photoreceptor;
Detecting a value of a current flowing through the photosensitive member or the charging roller by applying the voltage to the charging roller;
Obtaining an environmental value representing an environmental state in the image forming apparatus;
Executing the step of estimating the film thickness of the photoconductor based on the value of the current detected in the step of detecting when the state where the environmental value is within the predetermined range continues for a predetermined time or more. , An estimation program.